title: Imaging off-plane shear waves with a two-dimensional phononic crystal lens.
abstract: A two-dimensional flat phononic crystal (PC) lens for focusing off-plane shear waves is proposed. The lens consists of a triangular lattice hole-array, embedded in a solid matrix. The self-collimation effect is employed to guide the shear waves propagating through the lens along specific directions. The Dirichlet-to-Neumann maps (DtN) method is employed to calculate the band structure of the PC, which can avoid the problems of bad convergence and fake bands automatically in the void-solid PC structure. When the lens is illuminated by the off-plane shear waves emanating from a point source, a subwavelength image appears in the far-field zone. The imaging characteristics are investigated by calculating the displacement fields explicitly using the multiple scattering method, and the results are in good agreement with the ray-trace predictions. Our results may provide insights for designing new phononic devices.
authors.affiliation: Wave Engineering Laboratory, Department of Optics and Photonics, National Central University, Jhungli 320, Taiwan.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Chiang
authors.forename: Pi-Gang
authors.initials: PG
authors.lastname: Luan